If a heart beats too slowly, the pacemaker will use electrical signals to help set a normal rate.

VOA: special.2010.06.02

Here is as pacemaker and this pacemaker does the same thing that a heart pacemaker does, it generates periodic electrical signals.

它和心脏起搏器发挥的作用相似,发出周期性的电信号

耶鲁公开课 - 生物医学工程探索课程节选